[sdiy] Solder corrosion - what is it?

[Steve Lenham]

Hi,

I know there are some chemistry wizards on the list and wonder whether 
anyone could give me a bit of advice?

I'm working on some valuable musical equipment that has clearly been 
stored in a poor environment for a while. I don't know for sure, but am 
assuming it was just a generally damp place like a shed or cellar. As a 
result there is surface corrosion on many metal parts. This includes a 
light film of whitish-grey corrosion on exposed solder joints and tinned 
PCB tracks.

It's this last element that concerns me. It can be fairly easily scraped 
off mechanically where required, but I find myself wondering:

a) What exactly the substance is. Presumably it is either a tin or a 
lead compound?

b) Whether it represents any significant hazard to my health if I happen 
to disturb it. I'm not stupid - I don't intend to eat it, lick it or 
consciously inhale any of it but I am wondering whether I should take 
any special precautions if scraping any of it off (say to improve 
solderability when making repairs).

c) Whether this type of corrosion is - as it appears to the untrained 
eye - just a surface effect or whether it is likely to be affecting the 
integrity of solder joints.

Any illumination would be greatly appreciated!

Best regards,

Steve L.
Benden Sound Technology